As a test I decided to provide my services for the equivalent of 10GBP in BTC per hour.

If you have a project related to OpenGL, simple physics simulations
(rays, gravity) or signal processing (especially fourier transforms) contact me at whoplisp@gmail.com and I might decide to help you.

You would get a well thought through prototype to solve your problem (in Common Lisp) and test cases, so that you can check your own implementation. I am proficient in C but it is less fun (so for a C prototype I'll charge more).